EP09.05 EFFICACY OF MODERATE HYPOFRACTIONATED RADIOTHERAPY COMBINED WITH TEMOZOLOMIDE IN ELDERLY PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA: A SYSTEMATIC REVIEW AND META-ANALYSIS BASED ON THE KARNOFSKY SCALE

Abstract BACKGROUND Glioblastoma multiforme (GBM) is the most aggressive grade IV glioma in adults. While surgical resection followed by chemoradiotherapy remains the standard treatment, elderly patients (> 70 years) or those with poor functional status often cannot tolerate conventional radiotherapy regimens. The Karnofsky Performance Status (KPS), a widely used functional scale, has been identified as a key predictor of clinical benefit. This study evaluates the efficacy of different moderate hypofractionated radiotherapy (HFRT) regimens combined with temozolomide in newly diagnosed GBM patients, stratified by KPS. METHODS A systematic review was conducted using PubMed, Embase, Scopus, Web of Science, CENTRAL, and Google Scholar. Studies were included if they involved de novo GBM patients with a mean age > 70 years treated with moderate HFRT. Primary outcomes were overall survival (OS) and progression-free survival (PFS). Secondary outcomes included partial response (PR), stable disease (SD), and progression (PD) rates. A proportion meta-analysis was performed using a random-effects model in R Studio. Risk of bias was assessed using the ROBINS-I tool. RESULTS Nine studies met the inclusion criteria, encompassing a total of 342 patients, using HFRT regimens ranging from 30-52.5 Gy in 6-15 fractions. The longest PFS (8.5 months) was observed with 45 Gy in 15 fractions, while the highest OS (15.8 months) was reported with 40 Gy in 15 fractions. Pooled estimates were 0.13 (95% CI: 0.05-0.31) for PR, 0.05 (95% CI: 0.01-0.23) for SD, and 0.05 (95% CI: 0.01-0.28) for PD, with substantial heterogeneity. Most studies had a moderate to serious risk of bias. CONCLUSION Moderate hypofractionated radiotherapy (40-45 Gy in 15 fractions) combined with temozolomide appears to offer an optimal balance between efficacy and tolerability in elderly patients (> 70 years) with newly diagnosed GBM and a KPS > 70. Dose escalation showed no survival benefit and was associated with poorer outcomes in patients with lower KPS. Stratification by KPS remains essential for personalized treatment planning. Further prospective, well-designed clinical trials are needed to standardize radiotherapy dosing, improve patient selection criteria, and enhance therapeutic strategies based on functional status.